Ulgroth Crusade
|result=Stalemate |side1= |side2= |side3= |side4= |commanders1=*Sector Lord Orias Helracht XII |commanders2=*Sahrnab'Enaz'Zuk Zemor'Azus *Krathos Kalgorn *Aahrgoth the Conqueror *Mordenath the Knowing *Lorphus Ebolion *Salacior the Insatiable |commanders3= |commanders4= |forces1=*Local forces * ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **Pravini Shock Troops ** ** * **Warfleet Obscurus ***Battlefleet Ulgroth * **Aetherian Warriors **Apostles of Thanatos **Black Lions **Brothers of Eleos ** **Fire of Iapetus **Heimdallr's Legion **Hybris' Imperators **Icarus' Eagles **Imperial Uhlans **Jade Falcons **Knights of Sanguinor ** ** ** ** ** ** ** **Sons of Eleusis **Steel Raiders **War Claws * of the **Order of the Frozen Heart * ** *** *** *** |forces2=* *Traitorous PDF * * hordes *Various Legions and Warbands **Elements of the **Elements of the **Elements of the **Elements of the **Elements of the **Elements of the **Lords of Rot **Pillagers of Talos **Sons of Apmatenu **Oracles of Amenemhebi **Librarians of Tiumautef **Destroyers of Lexipheno **Servants of Ichor * ** *** *** |forces3= |forces4= |casual1=*Over one trillion total **Massive civilian casualties **85% of PDF forces **40% of total deployed Astra Militarum forces **60% of Battlefleet Ulgroth **30% of total deployed Adeptus Astartes forces ***Entire Icarus' Eagles Chapter ***Entire Sons of Eleusis Chapter **40% of total deployed Titan forces |casual2= Unknown |casual3= |casual4= }} The Ulgroth Crusade was a conflict fought in the Ulgroth , an -controlled region neighboring the . The conflict began with a rebellion on the oceanic world of Oseonus III in 960.M41, which quickly escalated into a full-blown invasion of the planet by the forces of . After successfully claiming control of Oseonus III, Chaos forces then commenced an invasion of the Ulgroth Sector as a whole. A number of worlds fell to Chaos before the invading forces were eventually fought to a stalemate in 975.M41 thanks to the intervention of over twenty , as well as the valiant efforts and strategic skill of Quentin Holgrim of Battlefleet Ulgroth. The Chaos-controlled portion of the Ulgroth Sector was later used as a staging area by forces during the . Order of Battle Prelude The Ulgroth Crusade broke out during the turbulent times preceding the beginning of the 13th Black Crusade. Though morale amongst Imperial forces in the was at a high point thanks to the recent Imperial victory in the bloody Verdictus Crusade in the previous year, unrest in the region was also mounting. Chaos activity around the was well above the norm and increasing rapidly, and sightings in and around the were at an all-time high. Cults of apostasy erupted through the regions near the Eye as many began to claim that the had forsaken them. This in turn allowed for the seeds of heresy to take hold on many planets in the area. Fall of Oseonus III Halius Aetherius on why he had to abandon the float-city of Osith Minor.}} Unrest in the Ulgroth Sector came to a head when Westmund Trant of Oseonus III declared his world's secession from the Imperium of Man. Oseonus III, an entirely oceanic world, fresh drinking water that was critical for numerous nearby systems as well as to the . With important resources at stake, the Imperium was quick to react, dispatching the Black Lions Space Marine Chapter as well as several and an Commandery to Oseonus III. However, upon arrival the situation was discovered to be far more grave than anyone thought: rebel forces were opening rifts in attempts to summon as well as to allow fearsome to come and aid them in their fight. With the risk of a possible daemonic incursion imminent, the Black Lions called upon the War Claws and Aetherian Warriors Chapters for aid. When the War Claws and Aetherian Warriors made landfall on one of Oseonus III's buoyant float-cities, specifically Hydroth, they were met with extremely heavy resistance from rebel forces, with a minor even being summoned, although it was unable to wreak much havoc before being beheaded by Corradina Breda of the Aetherian Warriors. Disturbed by the level of resistance encountered during their initial assault, Captain Breda called for additional reinforcements from the , who obliged Breda with a strike force from their Fourth Company, headed by Breda's long-time acquaintance, Egon Talorus. In the meantime, the Black Lions and a small detachment of Aetherian Warriors would focus their efforts on cutting off the rebels' access to supply depots on the float-city of Osith Minor, while Breda and Sabato Lepore of the War Claws would focus on taking the capitol, Osith Prime, starting by disabling artillery batteries being used by the rebels to bombard Loyalist forces in Hydroth.